1. Field of the Invention
The present invention relates to the field of flat panel displaying, and in particular to a pixel structure that eliminates vertical crosstalk and a liquid crystal display panel having the pixel structure.
2. The Related Arts
Liquid crystal displays (LCDs) have various advantages, including thin device body, saving power, and being free of radiation, and are thus widely used. Most of the liquid crystal displays that are currently available in the market are backlighting liquid crystal displays, which comprise an enclosure, a liquid crystal panel arranged in the enclosure, and a backlight module mounted in the enclosure. The principle of operation of the liquid crystal panel is that liquid crystal molecules are arranged between two parallel glass substrates and electricity is applied to control the liquid crystal molecules to change direction in order to refract light emitting from the backlight module to pass through a pixel structure formed on the glass substrates to generate a color image.
Since an upper substrate (the array substrate) and a lower substrate (the color filter (CF) substrate) of a liquid crystal panel are bonded together by means of circumferentially-arranged enclosing resin, it is very likely that relative positional shift may occur in a display zone. If the relative positional shift may make a black matrix (BM) formed on the upper substrate not effectively shielding light leaking areas around data lines on the lower substrate, a situation of poor displaying where light leaking occurs in a dark image located in a vertical direction of a bright image, which is referred to as vertical crosstalk (V-crosstalk).
Positional shift between a lower substrate and an upper substrate of a liquid crystal panel resulting in vertical crosstalk is demonstrated in FIGS. 1-5, in which FIG. 1 is a schematic view showing the structure of a pixel structure manufactured with a five-mask process. When a signal applied to a data line is kept at a low biasing voltage (as shown in FIG. 2), no rotation of liquid crystal will occur on opposite sides thereof (see FIG. 3) and thus no light leaking zone is induced. If the signal applied to the data line 100 is a high biasing voltage at one time and is a low biasing voltage at another time (as shown in FIG. 4), then in the period when the signal of the data line 100 is the high biasing voltage, rotation of liquid crystal will occur on opposite sides of the entirety of the data line, thereby resulting in the formation of light leaking area (as shown in FIG. 5).
Ideally, to maximize the aperture ratio of a pixel, a designer would wish to have the black matrix 200 can provide shielding that just covers edges of the aperture area of a pixel electrode (ITO) 300 (see FIG. 6). However, to prevent vertical crosstalk, a common solution is to widen the black matrix 200 to have the black matrix 200 shielding a further distance X1 into the aperture area (see FIG. 7). The value of X1 is determined by the positional shift between the upper and lower substrates, while the positional shift is determined by the actual conditions of the panel and is generally between 0-30 μm. The greater the positional shift is, the greater the chance of causing vertical crosstalk will be. Generally, the value of X1 is set between 2 μm-20 μm. The greater the value of X1 is, the greater the loss of the aperture ratio will be. However, for a regular pixel structure (as shown in FIG. 8), since an aperture area 400 is provided on both the left side and the right side thereof with data lines 100, the loss of the area of the aperture area 400 of each pixel is equal to 2X1*H1 (where H1 is an effective height of the aperture area 400) and this causes an increased loss of the aperture ratio.